1. Field of the Invention
This invention relates to a connector, and more particularly to a connector which is suitable for high-speed transmission of signals.
2. Description of the Related Art
Conventionally, there has been proposed a connector comprised of a housing and a plurality of contact groups (see Japanese Laid-Open Patent Publication (Kokai) No. 2007-179970).
The plurality of contact groups are held by the housing, and are arranged side by side in a row along the direction of the width of the housing.
One contact group is formed by a ground contact, a first signal contact, and a second signal contact.
The ground contact includes a first contact portion and a first connection portion. The first signal contact includes a second contact portion and a second connection portion. The second signal contact includes a third contact portion and a third connection portion.
The first contact portions, the second contact portions, and the third contact portions of the plurality of contact groups are arranged side by side in a row along the direction of the width of the housing. These contact portions are regularly arranged in the order of the first contact portion, the second contact portion, and the third contact portion, and hence the second contact portion of each first signal contact and the third contact portion of each second signal contact are sandwiched by the first contact portions of two ground contacts (except for the first and second signal contacts of a contact group disposed at the right end in the direction of the width of the housing).
In each contact group, an isosceles triangle is formed by connecting the first connection portion, the second connection portion, and the third connection portion by imaginary straight lines. Further, a zigzag curved line is formed by connecting the first connection portions of the respective contact groups with each other by imaginary straight lines. The first to third connection portions of the contact groups are arranged in upper and lower two rows along the direction of the width of the housing. In the upper row, the first to third connection portions of the contact groups are regularly arranged in the order of a first connection portion, a second connection portion, and a third connection portion. Therefore, in the upper row, the respective connection portions of the first and second signal contacts of each same contact group are sandwiched by the connection portions of two ground contacts of respective other contact groups (except for the first and second signal contacts of the contact group disposed at the right end in the direction of the width of the housing). In the lower row, the first to third connection portions of the contact groups are regularly arranged in the order of a second connection portion, a third connection portion, and a first connection portion. Therefore, in the upper row, the connection portions of the first and second signal contacts of each same contact group are sandwiched by the connection portions of two ground contacts of respective other contact groups (except for the first and second signal contacts of a contact group disposed at the left end in the direction of the width of the housing).
As described above, the first to third contact portions are arranged in a row along the direction of the width of the housing, and the first to third connection portions are arranged in two rows along the direction of the width of the housing. This makes it possible to make the pitch of arrangement of the connection portions two times as wide as that of arrangement of the contact portions. Thus, the pitch of the arrangement of connection portions can be made larger than that of the arrangement of the contact portions, and hence it is possible to easily perform connection operations even if the pitch of the arrangement of the contact portions is reduced.
In the above-described connector, the contact portions of the first and second signal contacts of the contact group disposed at the right end in the direction of the width of the housing is not sandwiched by the contact portions of ground contacts, as described above. For this reason, variation occurs in impedance between the contact group and the other contact groups, which causes degradation of transmission characteristics.
Further, the arrangement of the connection portions in the upper row and that of the connection portions in the lower row is displaced by half of a pitch thereof in the direction of the width of the housing, and the second connection portion of one of adjacent contact groups and the third connection portion of the other of the adjacent contact groups are diagonally close to each other via a gap without the connection portion of a ground contact interposed therebetween, so that the degree of connection between these connection portions becomes large, which causes cross talk, degrading transmission characteristics.